This invention relates to flavanone compounds. More particularly, it relates to a limited class of sulfonate-group-containing flavanones.
Flavanones have been known since the nineteenth century. They occur in nature and have been synthesized in the laboratory. They are known to enter into a wide range of chemical reactions. In one reaction sequence, they can be isomerized with base to give chalcones which can then be hydrogenated to yield dihydrochalcones. This sequence is exemplified by the following conversion of the naturally occurring flavanone, naringin, to naringin dihydrochalcone: ##STR2##
Flavanones and their conversion to dihydrochalcones took on special interest in the early nineteen-sixties when it was discovered that dihydrochalcones formed from the flavanones prunin, naringin, and neohesperidin were intensely sweet. These flavanones which in the art gave sweet dihydrochalcones may be chemically characterized as having large glycoside residues attached via an oxygen bond links to their left most aromatic rings. I.e., R in the above formulae is a glycoside such as .beta.-neohesperidosyl, .beta.-rutinosyl or the like. While they yield sweet dihydrochalcones, such flavanones themselves are generally bitter or tasteless. In fact, naringin (the principle bitter compound in grapefruit rind) finds commercial application as a bittering agent in some tonic water formulations. Horowitz, in Chapter 14 of Biochemistry of Phenolic Compounds, Harborne Ed., (Academic Press, 1964) pages 555-556 reports that, aside from one material, hesperetin, which has slight sweetness, flavanones useful as dihydrochalcone sweetener precursors which he examined were tasteless or bitter. Similar results are reported by Horowitz and Gentile at Agr. and Food Chem. Volume 17, No. 4 p. 696 (1969) and by Kamiya et al at Agr. Biol. Chem. Volume 39, p. 1757 (1975).